Technical Field
The present disclosure relates to a dust seal for preventing entry of foreign matter such as dust, rain, or the like, and particularly relates to a steering dust seal for a steering shaft of a steering device for a car or other vehicles.
Background Art
In a steering device for a vehicle, e.g. a car, a steering shaft is inserted through a column hole opened in the dash panel separating the vehicle interior and the engine room. A gap between the steering shaft and the column hole is sealed with a steering dust seal. The steering dust seal prevents entry of foreign matter such as dust, rain, or the like to the vehicle interior.
FIG. 6 is a cross-sectional view schematically showing the structure of a conventional dust seal. As shown in FIG. 6, a dust seal 100 as a conventional steering dust seal includes a cylindrical bushing 101 made of a low-friction material, a dust seal body 102 made of a rubber, a annular seal lip 103, which is present at an end portion of the bushing 101 adjacent to the engine room, and a attaching member 104.
A steering shaft 130 is inserted through the bushing 101, and the bushing 101 is slidable on the steering shaft 130. The dust seal body 102 includes a first bellows (accordion unit) 105 and a second bellows 106, which project toward the engine room, and a cylindrical attaching portion 107 joined to the end portions of the first and second bellows 105 and 106 on the outer periphery side. A cylindrical metal reinforcing ring 108, which serves as a reinforcement conforming to the shape of the attaching portion 107, is embedded in the attaching portion 107. An inner end portion 105a of the first bellows 105 and an inner end portion 106a of the second bellows 106 are fitted in the outer periphery of an end portion 101a of the bushing 101 adjacent to the vehicle interior.
The attaching member 104 is an annular metal member that has a cross section in a generally L shape fitted in the inner end portion 105a on the inner side so as to cover the inner end portion 105a of the first bellows 105. Since the attaching member 104 is fitted in the inner end portion 105a of the first bellows 105 in this manner, the inner end portion 105a of the first bellows 105 is locked in a direction toward the vehicle interior side and pushed toward the inner periphery side, therefore, the first bellows 105 is fixed to the end portion 101a of the bushing 101 adjacent to the vehicle interior, at the inner end portion 105a. In addition, as shown in FIG. 6, the inner end portion 106a of the second bellows 106 is locked in a direction toward the vehicle interior by the inner end portion 105a of the first bellows 105 fixed as described above, pushed toward the inner periphery side, and fixed to the end portion 101a of the bushing 101 adjacent to the vehicle interior.
The seal lip 103, which is a rubber annular member, is disposed at the end portion 101b of the bushing 101 adjacent to the engine room and is slidably in contact with a surface of the steering shaft 130. The seal lip 103 prevents entry of foreign matter such as rain, dust or the like to a space between the steering shaft 130 and the bushing 101, and leakage of a lubricant on the inner periphery of the bushing 101.
As shown in FIG. 6, in the dust seal 100, the attaching portion 107 of the dust seal body 102 is closely fitted in a column hole 132 of a dash panel 131 for fixation to the column hole 132 of the dash panel 131. Hence, entry of foreign matter such as rain, dust or the like in the gap between the dust seal 100 and the column hole 132 is prevented (for example, see Japanese Patent No. 4987300).
With this structure in the conventional dust seal 100, the bushing 101 is movable with the first and second bellows 105 and 106 relatively to the dash panel 131 (the column hole 132). The steering shaft 130 is tilted or displaced and moves relatively to the column hole 132 due to adjustment of the handle level or vibrations occurring while the car is running. However, the bushing 101 movable relatively to the column hole 132 can follow the movement of the steering shaft 130. This maintains the position of the seal lip 103 and thus works for ensuring prevention of entry of foreign matter such as rain, dust, or the like from the engine room to the vehicle interior.
In the conventional dust seal 100, the bushing 101 is separated from the first bellows 105 and the second bellows 106, resulting in a large number of components and a complex assembly process of the conventional dust seal 100. In addition, the first bellows 105 and the second bellows 106 are attached to the bushing 101 by fitting the attaching member 104, so that adequate attaching strength is not provided and the deviation or vibration of the steering shaft 130 may unlock the mounting member 104 and remove the fixation between each of the first bellows 105 and the second bellows 106 and the bushing 101. Even if the attaching member 104 does not come off, loosened fixation between each of the first bellows 105 and the second bellows 106 and the bushing 101 prevents the bushing 101 and thus the seal lip 103 from staying in their proper positions, and there may be a problem with a decrease in sealing performance between the seal lip 103 and the steering shaft 130.
The present disclosure is related to providing a dust seal which can be made with a simple assembly process and exhibits high joint strength between the bushing and each accordion unit.